A Fourplex is a multifamily residential building with four units under the same roof. There are a few different layouts of a fourplex.
The fourplex also benefits from qualifying for traditional residential financing. A fourplex still qualifies for Freddie Mac 30 year fixed mortgages.
The biggest benefit to househacking is that the tenants are paying the mortgage for what is typically your biggest living expense. Your housing. The other major benefit is in financing.
When evaluating investment opportunities, you will go through a process to source, compare and underwrite them.